PLL Oscillator Downshift Using Open-Loop Frequency Control
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Solution Overview
Problem
Phase-locked loops in computing devices face challenges in rapidly changing frequencies, leading to voltage drops and potential errors due to their nature of requiring feedback loops, which hinder quick adjustments during current surges.
Innovation Solution
The implementation of a switch to an open-loop mode in the feedback loop, triggered by voltage events, allows for rapid frequency downshift of oscillators, reducing power consumption and preventing errors by freezing control signals and using auxiliary control signals to adjust frequencies quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a feedback loop is used to control oscillator frequency, then frequency stability is improved, but frequency change speed deteriorates
Solution Approach 1:
The system dynamically switches between closed-loop mode (for frequency stability) and open-loop mode (for rapid frequency changes). The feedback loop is selectively enabled or disabled based on whether frequency accuracy or speed of change is the priority, allowing the system to adapt its control characteristics in real-time.
Solution Approach 2:
The frequency control process is segmented into two distinct phases: closed-loop frequency acquisition/adjustment phase and open-loop rapid change phase. This segmentation allows each phase to optimize for its specific goal without being constrained by the other phase's requirements.
2Reliability
If frequency is downshifted rapidly during voltage drops, then error prevention is improved, but additional current steps are generated
Solution Approach 1:
The patent converts the harmful effect of frequency downshifting (which generates current steps) into a beneficial protective measure. By carefully controlling the downshift timing and magnitude, the system uses the current step from frequency change as a controlled response to prevent larger harmful current steps that would occur from voltage droop errors.
Solution Approach 2:
The system changes the oscillator frequency parameter in response to detected voltage drops. By adjusting the frequency parameter dynamically, the system reduces power consumption and prevents timing errors without requiring changes to the voltage supply or hardware configuration.
Data Source
AI summary
Techniques are disclosed relating to rapidly downshifting the output frequency of an oscillator. In some embodiments, the oscillator is configured to operate in a closed-loop mode in which negative feedback is used to maintain a particular output frequency (e.g., in a phase-locked loop (PLL)). In some embodiments, the negative feedback loop is configured to maintain the output of the oscillator at a particular frequency based on a reference clock signal and the output of the oscillator. The nature of a negative feedback loop may render rapid frequency changes difficult, e.g., because of corrections by the loop. Therefore, in some embodiments, the loop is configured to switch to an open-loop mode in which a control input to the oscillator is fixed. In some embodiments, the loop switches to open-loop mode in response to a trigger signal and control circuitry forces the oscillator to a new target frequency.